(warning: this post, aside from Scripture quotations, is my opinion, which probably means it's wrong)Someone's already brought it up, but:2 Corinthians 9:7As every man purposeth in his heart, so let him give, not grudgingly or out of compulsion; for God loveth the cheerful giver. I don't believe that Christians are commanded in Scripture to "tithe," or to give any particular percentage (thank you, Brother Mike, for that linking to that light-shedding article).I believe Christians are commanded to be responsible with everything God gives them (money and other resources, time, relationships, talents, gifts, oppurtunities, their bodies, etc). Relating to money, this means we should have some kind of God-centered purpose for every dollar (or pound, or frank, whatever). We have a responsibility to provide for our immediate family:1 Timothy 5:8But if any provide not for his own, and especially for those of his own house, he hath denied the faith and is worse than an infidel.So, if we're responsible for our house's finances, we should save enough money to tend to our family's material needs, though of course we should closely examine the expenditures and make sure they are for a God-centered purpose.If we have no one else under us (i.e. no 'house') I believe we should save enough to tend to our own (again, carefully examined) needs rather than have to ask another for support and thus become a burden.Some things require long-term saving (houses, higher education for children, etc.), and if it's for a Godly purpose I don't see anything "covetous" (i.e. greedy) with saving for them. Again, prayerful examination...(edit)The government wants it's taxes, too, so estimate how much the legalized thieves (minor sarcasm) will demand and save enough so that you won't get put in jail. Give unto Caesar what is Caesar's is the principle, I suppose.Once those needs are met, give the rest away. That's my opinion, at least. Certainly, don't be haphazard, pray God's guidance and wisdom in giving, and I think it's good to have a few people in the local church concentrate on finding genuine needs and directing charity towards them.There, you asked my opinion, you got it :)If you want something that's actually correct, I think Crown Financial Ministries has some pretty good teachings, though I haven't looked through them myself... I probably should though (mental to-do list ammended).